::: TASMANIA'S NATIVES


Butterflies of Tasmania

By Dr PHIL BELL| Less than 40 species of butterflies are native to Tasmania — and skippers, swallowtails, browns and blues are the romantic names for the four major groups to which they belong.

Skippers

Skippers are small to medium-sized and generally have a rapid and erratic flight pattern, hence their common name ‘skipper’. Eleven species are known in Tasmania.

Two species are listed as threatened under Tasmanian legislation. The chaostola skipper is restricted to a few localities on the east coast — you’ll see them on the wing in open eucalypt forests, if you’re lucky, from mid-October to mid-December.

The Marrawah skipper, which is restricted to a very small area around Marrawah in the far north-west, takes to the air mid-January to mid-February.

Browns, from small to large

These commonly seen butterflies are associated with grasses and sedges and can be seen across Tasmania, both in the bush and around towns and cities.

The browns range in size from small butterflies, like the common silver xenica, to medium-sized butterflies, like the common brown. A couple of visitors from mainland Australia — the wanderer and the lesser wanderer — are larger with wingspans approaching 10cm.

As Peter McQuillan notes in Butterflies of Tasmania (more below), wanderers are well named, spreading from their North American origins all around the globe in the 19th century, reaching Australia by about 1870.

Fourteen species of browns are found in Tasmania, several of which have a preference for higher altitudes, while the Hobart brown is one of the earliest butterflies to emerge in spring.

The brown-black supspecies sometimes called the Tasmanian brown flies from October to November in the west and south-west and bushwalkers could come across it in buttongrass plains where there are patches of forest.

One species, ptunarra brown, is listed as threatened due to the loss and degradation of its habitat. Poa grass tussocks are the food plant of ptunarra brown’s caterpillars.

This species has become a flagship in the conservation of native grasslands in Tasmania and its survival is closely tied to the conservation of poa grasslands and grassy woodlands in this State.

Blues — in colours too

The blues, oddly enough, are blue or brown or orange in colour and usually small in size.

The caterpillars are often associated with particular species of ants — the ants protecting the caterpillars from predators and the caterpillars providing the ants with food secretions such as honeydew.

There are several subspecies, some showing strong regional differences. For example, the Tasmanian hairstreak exists in pockets from Port Sorell south to Hobart in the eastern part of the state, and prefers wattles.

The chequered blue can be found in saltmarsh, as near Cambridge Airport, Hobart, and has been recorded on Flinders Island.

The long isolation during the ice ages is also thought to have led to geographical differences in Tasmanian butterflies from their mainland counterparts.

Atracting attention — the swallowtail

Swallowtails include some of the largest and most impressively coloured butterflies in the world. However, Tasmania has only one species, Macleay’s swallowtail, which has a wingspan of about 7cm — which makes this butterfly large by Tasmanian standards.

It attracts attention for its contrasting green and black colour. The caterpillars feed on sassafras, a common tree of Tasmania’s rainforest. Its flight period is from November to March and it’s all around Tasmania wherever the sassafras grows.

In the northern hemisphere butterflies have been used as convenient indicator species for monitoring climate change and pollution, as well as the loss and degradation of native habitats.

Tasmania’s butterflies have received only limited attention in terms of the study of their biology and ecology.

Further study, particularly on our unique and interesting species will help us better understand how to conserve individual species, and perhaps, help us to explore the potential for using butterflies in Tasmania as a tool for monitoring environmental change.

Cabbage whites — transplants from Europe

There is one notable introduced species, the cabbage white, which belongs to a group known as the whites, a group not represented by Tasmanian native species.

The cabbage white arrived in Australia in the 1930s from Europe and became established in Tasmania in the early 1940s. This is the butterfly whose green caterpillars eat our broccoli, cauliflower and cabbages in the backyard vegie patch.

The beautiful watercolour illustrations in the book — some of which you see here — were painted by Julie Virtue, whose natural history and floral landscape paintings are internationally acclaimed and sold.

To see the butterflies for yourself, you'll find an exhibit at the Tasmanian Museum and Art Gallery, Hobart.

It's not large (there are more due for display when the Museum opens a new exhibit centre in Rosny, although that's not for some time), but it does show the exquisite colouring and markings of our Tasmanian butterflies when you examine them in the Zoology display on the ground floor of the Museum. ¶